1. Field of the Invention
This invention relates to a drive pulley for hauling equipment, and in particular, a rope or cable drive pulley for cableways, comprising a hub, a rim and spokes between the hub and ring serving as connecting elements. The individual spokes are arranged independently from one another.
The first known rope pulleys of this kind were built in accordance with a wagon wheel. From a small hub radially arranged spokes, usually eight in number, extended to the rim in such known pulleys. The expression "extending independently from one another" in the context of drive pulleys means, with respect to the spokes, that the individual spokes are not directly interconnected, e.g., by cross-over points and accordingly, that common areas of contact at the hub or the rim can only arise at the connecting point. Sheet metal panels inserted locally between adjoining spokes are not considered direct connections in the above sense. As the required capacities and lifting height requirements increased in the construction of such installations, the spoke connections due to increased tangential loads have become increasingly more expensive. The thicknesses of the spokes themselves had to be increased and accordingly their masses increased as well and economics suffered.
2. Description of the Related Art
U.S. Pat. No. 1,694,350 describes a further development, comprising a rope drive pulley, in which the spokes directly fitted to the hub extend obliquely to the radii of the pulley. The connecting points of the spokes to the rim, and respectively, to the hub, are in each case equidistant.
A further alternative solution was proposed in the form of the so-called solid pulley. In this case the connecting member between the hub and the rim takes the form of a continuous surface, usually reinforced by preferably eight radial struts. The advantages resided of this construction reside in an increase in the transmissible drive capacity combined with increased operational reliability. In order to somewhat mitigate the drawback of the high mass, substantially circular holes have been provided in the region between the struts. In the course of time this type of pulley was modified in a variety of manners. For example by the sheet metal panel was doubled, to provide a construction similar to a sandwich construction. The general principle of the solid pulley was retained, however.